This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics committee. The paper was approved by the committee on May 16, 1999, and by the AGA governing board on July 18, 1999.

This document presents the official recommendations of the American Gastroenterological Association (AGA) on the evaluation and management of occult and obscure gastrointestinal bleeding. It was approved by the Clinical Practice and Practice Economics Committee on May 16, 1999, and by the AGA governing board on July 18, 1999.

This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics Committee. The paper was approved by the Committee in March 1999 and by the AGA Governing Board in May 1999.

This document presents the official recommendations of the American Gastroenterological Association (AGA) on the Epidemiology, Diagnosis, and Treatment of Pancreatic Ductal Adenocarcinoma. It was approved by the Clinical Practice and Practice Economics Committee in March 1999 and by the AGA Governing Board in May 1999.

Enteric ganglia can maintain integrated functions, such as the peristaltic reflex, in the absence of input from the central nervous system, which has a modulatory role. Several clinical and experimental observations suggest that homeostatic control of gut function in a changing environment may be achieved through adaptive changes occurring in the enteric ganglia. A distinctive feature of enteric ganglia, which may be crucial during the development of adaptive responses, is the vicinity of the final effector cells, which are an important source of mediators regulating cell growth. The aim of this review is to focus on the possible mechanisms underlying neuronal plasticity in the enteric nervous system and to consider approaches to the study of plasticity in this model. These include investigations of neuronal connectivity during development, adaptive mechanisms that maintain function after suppression of a specific neural input, and the possible occurrence of activity-dependent modifications of synaptic efficacy, which are thought to be important in storage of information in the brain. One of the applied aspects of the study of plasticity in the enteric nervous system is that knowledge of the underlying mechanisms may eventually enable us to develop strategies to correct neuronal alterations described in several diseases.

The relationship between chronic inflammatory conditions and malignancy is complex. We describe the clinical course of 2 patients with Crohn's disease (CD) in whom lymphoma was diagnosed after treatment with infliximab. The first patient was a 61-year-old man with a 30-year history of fistulizing CD in whom B-cell non-Hodgkin's lymphoma was diagnosed 9 months after treatment with infliximab. The second is a 29-year-old man with CD in whom nodular sclerosing Hodgkin's lymphoma was diagnosed 3 weeks after infusion with infliximab. The lymphoma presented with pleural effusions, mediastinal and cervical adenopathy, and no gastrointestinal lesion. We describe the implications of these cases for the use of immunomodulatory therapy in CD and the questionable association between CD and lymphoma.